Light emitting diode and light emitting device

Abstract

According to the light-emitting diode and the light-emitting device provided by the invention, a current blocking layer above the second semiconductor layer is canceled, so that a material layer generating light absorption is reduced, and reflected light can be increased; besides, by improving the material of the metal electrode and selecting technical materials with high reflectivity, such as Cr / Ag, Ti / Ni / Ag and the like, the reflectivity of the metal electrode is improved, and the reflection of the metal electrode to light is increased. According to the invention, the ALD layer is formed between the DBR structure and the metal reflection electrode layer, and the ALD layer can effectively prevent Ag in the metal electrode from migrating and diffusing into the semiconductor layer to affect the reliability of the light-emitting diode. In addition, the side wall of the ALD layer has a smaller inclination angle than the side wall of the DBR structure, and the arrangement of the angle is beneficial to the coverage of a metal material when a metal electrode layer is subsequently formed, and the reliability of the electrode structure is improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor devices and apparatus, and particularly to a light-emitting diode and a light-emitting device. Background Technology

[0002] Light-emitting diodes (LEDs) have advantages such as high luminous intensity, high efficiency, small size, and long lifespan, and are considered one of the most promising light sources today. In recent years, LEDs have been widely used in daily life, such as lighting, signal display, backlighting, automotive lights, and large-screen displays. At the same time, these applications have also placed higher demands on the brightness and luminous efficiency of LEDs.

[0003] For flip chips, the light emitted from the light-emitting layer is mainly reflected to the back of the chip by the diffuse reflector (DBR) layer on the front side of the chip. In existing flip chips, the DBR film is the main reflective structure, and the reflectivity of the metal electrode part on the front side of the chip is relatively poor. This means that the light incident on the metal electrode part cannot be reflected, which is not conducive to improving the light extraction efficiency of the LED chip. Summary of the Invention

[0004] In view of the poor light emission effect of light-emitting diodes in the prior art due to reflectivity issues, the present invention provides a light-emitting diode and a light-emitting device to solve one or more of the above-mentioned problems.

[0005] One embodiment of this application provides a light-emitting diode, which includes at least: A semiconductor epitaxial stack includes a first semiconductor layer, an active layer, and a second semiconductor layer stacked sequentially; the semiconductor epitaxial stack has a first mesa and a second mesa, the surface of the first mesa is the exposed first semiconductor layer, the surface of the second mesa is the second semiconductor layer, the first mesa is lower than the second mesa, one side of the semiconductor epitaxial stack forming the first mesa and the second mesa is the front side, and the side opposite to the front side is the back side, the back side is the light-emitting surface of the light-emitting diode; An ALD protective layer covers the surfaces and sidewalls of the first and second platforms, and a first electrode through-hole is formed above the first and second platforms; An insulating reflective layer is located above the ALD protective layer. A second electrode via is formed in the region corresponding to the first electrode via. At the first electrode via, there is a first included angle α between the sidewall of the ALD and the surface of the reflective metal layer. At the second electrode via, there is a second included angle β between the sidewall of the insulating reflective layer and the surface of the reflective electrode layer, and α < β.

[0006] Another embodiment of this application provides a light-emitting device, which includes a circuit board and a light-emitting element disposed on the circuit board, wherein the light-emitting element includes the light-emitting diode provided in this application.

[0007] As described above, the light-emitting diode and light-emitting device of this application have the following beneficial effects: This application eliminates the current blocking layer above the second semiconductor layer in its light-emitting diode (LED), thus reducing the amount of light-absorbing material and increasing the amount of reflected light. Furthermore, by improving the material of the metal electrode, selecting a metal material with high reflectivity, such as Cr / Ag, Ti / Ag, Ni / Ag, Ti / Ni / Ag, Ni / Ti / Ag, Cr / Ti / Ag, or Ag, the reflectivity of the metal electrode is increased, thereby increasing the reflection of light by the metal electrode. This application forms an ALD layer between the DBR structure and the metal reflective electrode layer. This ALD layer effectively prevents Ag from migrating and diffusing from the metal electrode into the semiconductor layer, thus affecting the reliability of the LED. Additionally, the sidewalls of this ALD layer have a smaller tilt angle than the sidewalls of the DBR structure. This angle improves the coverage of the metal material during the subsequent formation of the metal electrode layer, enhancing the reliability of the electrode structure. Attached Figure Description

[0008] Figure 1 The diagram shown is a schematic diagram of the structure of a flip-chip light-emitting diode in the prior art.

[0009] Figure 2 The diagram shown is a schematic diagram of the structure of a light-emitting diode provided in Embodiment 1 of the present invention.

[0010] Figure 3 Displayed as Figure 2 A partially enlarged structural diagram of the middle rectangular frame D1.

[0011] Figure 4 Displayed as Figure 2 The diagram shows a brightness comparison between the light-emitting diode (LED) and LEDs in the prior art.

[0012] Figure 5 Displayed as Figure 2 The diagram shows a voltage comparison between the LED shown and LEDs in the prior art.

[0013] Figure 6 The diagram shown is a schematic diagram of the structure of a light-emitting diode provided in Embodiment 2 of the present invention.

[0014] Figure 7 Displayed as Figure 6 A magnified schematic diagram of the structure of part D2 of the middle rectangle.

[0015] Figure 8 The diagram shown is a schematic diagram of the light-emitting device provided in Embodiment 4 of the present invention.

[0016] Component designation explanation 11. N-type semiconductor layer; 12. Active layer; 13. P-type semiconductor layer; 14. Current blocking layer; 15. Transparent conductive layer; 16. Connecting electrode layer; 17. DBR structure.

[0017] 100, Light Emitting Diode; 110, Substrate; 111, Front Side; 112, Back Side; 120, Semiconductor Epitaxial Stack; 1201, First Mesa; 1202, Second Mesa; 121, First Semiconductor Layer; 122, Active Layer; 123, Second Semiconductor Layer; 130, Transparent Conductive Layer; 141, First Connecting Electrode; 142, Second Connecting Electrode; 1421, First Layer Structure; 1422, Second Layer Structure; 150, ALD Protective Layer; 1501, First Electrode Via; 160, Insulating Reflective Layer; 1601, Second Electrode Via; 171, First Metal Electrode Layer; 172, Second Metal Electrode Layer; 1721, First Metal Layer; 1722, Second Metal Layer; 181, First Pad; 182, Second Pad; 190, Insulating Protective Layer.

[0018] 200, Light-emitting device; 201, Circuit board; 202, Light-emitting unit. Detailed Implementation

[0019] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0020] like Figure 1 As shown, in the prior art, a light-emitting diode (LED) includes an epitaxial stack, which comprises an N-type semiconductor layer 11, an active layer 12, and a P-type semiconductor layer 13 stacked sequentially. A transparent conductive layer 15 is formed above the P-type semiconductor layer 13 and is electrically connected to the connection electrode 16 on the P-side to improve the lateral current spread on the P-type semiconductor layer 13 side. Simultaneously, to reduce current concentration near the connection electrode 16, a current blocking layer 14 is typically formed below the transparent conductive layer 15 in the region corresponding to the connection electrode 16. This current blocking layer 14 is typically an insulating material such as silicon oxide, which absorbs some light, affecting the light extraction efficiency of the LED. As a flip-chip LED, it mainly reflects the light radiated from the active layer 12 through the DBR structure 17. Since the metal electrodes of the chip are all formed on the front side of the chip, and the reflectivity of the metal electrodes is relatively poor, not all light incident on the metal electrode portion can be reflected, which is detrimental to improving the light extraction efficiency of the LED chip.

[0021] To address the shortcomings of existing light-emitting diodes (LEDs) in terms of poor light emission performance due to reflectivity issues, one embodiment of this application provides an LED that includes at least: A semiconductor epitaxial stack includes a first semiconductor layer, an active layer, and a second semiconductor layer stacked sequentially; the semiconductor epitaxial stack has a first mesa and a second mesa, the surface of the first mesa is the exposed first semiconductor layer, the surface of the second mesa is the second semiconductor layer, the first mesa is lower than the second mesa, one side of the semiconductor epitaxial stack forming the first mesa and the second mesa is the front side, and the side opposite to the front side is the back side, the back side is the light-emitting surface of the light-emitting diode; An ALD protective layer covers the surfaces and sidewalls of the first and second platforms, and a first electrode through-hole is formed above the first and second platforms; An insulating reflective layer is located above the ALD protective layer. A second electrode via is formed in the region corresponding to the first electrode via. At the first electrode via, there is a first angle α between the sidewall of the ALD and the plane containing the surface of the second semiconductor layer. At the second electrode via, there is a second angle β between the sidewall of the insulating reflective layer and the plane containing the surface of the second semiconductor layer, and α < β.

[0022] Optionally, the first included angle α satisfies: 10°≤α≤30°.

[0023] Optionally, the second included angle β satisfies: 30°≤β≤60°.

[0024] As described above, an ALD protective layer is formed between the insulating reflective layer and the transparent conductive layer. The sidewalls of the ALD protective layer have a smaller tilt angle than the sidewalls of the insulating reflective layer; that is, the sidewalls of the ALD protective layer are more gently sloping than the sidewalls of the insulating reflective layer. The gradual change in the tilt angle between the sidewalls of the ALD protective layer and the insulating reflective layer allows for a better transition of the metal coverage effect. This is beneficial for improving the adhesion and uniformity of the metal material during the subsequent formation of the electrode structure, preventing cracks or breaks in the metal layer, and improving the stability and reliability of the electrode structure.

[0025] Optionally, the light-emitting diode further includes: A transparent conductive layer is formed above the second semiconductor layer; An electrode structure includes a first electrode formed on the surface of the first mesa and electrically connected to the first semiconductor layer, and a second electrode formed on the surface of the second mesa and electrically connected to the second semiconductor layer; in a direction away from the second semiconductor layer, the second electrode includes a reflective electrode layer formed above the transparent conductive layer.

[0026] Optionally, the first electrode via exposes the reflective electrode layer, and the ALD protective layer covers the edge region of the reflective electrode layer, wherein the reflective electrode layer comprises two or more metal material layers with different refractive indices.

[0027] As described above, the second electrode electrically connected to the second semiconductor layer (i.e., the P-type semiconductor layer) in this application includes a reflective electrode layer. This reflective electrode layer can be a second connection electrode electrically connected to the transparent conductive layer, and its forming material is, for example, a Cr / Ag metal layer. This metal layer has good reflective properties and can reflect incident light, thereby improving the light emission efficiency of the light-emitting diode. Simultaneously, the ALD layer covers the reflective electrode layer, effectively preventing the diffusion or migration of metal therein into the semiconductor layer, thus improving the reliability of the light-emitting diode. Furthermore, no current blocking layer is provided directly below the second electrode, thereby reducing the amount of absorbed light and allowing more light to be reflected, improving the light emission efficiency of the light-emitting diode.

[0028] Optionally, the reflective electrode layer at least fills the first electrode via above the second platform and covers the edge region of the ALD protective layer, and the reflective electrode layer comprises two or more metal material layers with different refractive indices.

[0029] In an optional embodiment, the second electrode on one side of the second semiconductor layer of the light-emitting diode (LED) may not form a connecting electrode; instead, a metal electrode layer can be directly formed that is electrically connected to the transparent conductive layer. The side of the metal electrode layer adjacent to the transparent conductive layer is formed as a reflective electrode layer. This reflective electrode layer is made of a material such as a Ti / Ni / Ag metal layer, which also has good reflective properties and can reflect incident light, thereby improving the light extraction efficiency of the LED. An ALD protective layer is located between the reflective metal layer and the transparent conductive layer, which also prevents the metal from diffusing or migrating into the semiconductor layer through the edge of the transparent conductive layer, thus improving the reliability of the LED.

[0030] Optionally, the second electrode further includes a metal electrode layer located above the insulating reflective layer and filling the first electrode via and the second electrode via above the second platform. The metal electrode layer includes at least an Al layer, and the Al layer is disposed adjacent to the reflective electrode layer.

[0031] The metal electrode layer contains Al, a metal with high reflectivity, which further increases the reflection of incident light and improves the light extraction efficiency of the light-emitting diode.

[0032] Optionally, the second electrode further includes a metal electrode layer located above the insulating reflective layer and filling the second electrode via above the second mesa, wherein the metal electrode layer is a Cr / Al metal layer.

[0033] At this point, the aforementioned metal electrode layer includes the aforementioned reflective electrode layer and the Cr / Al metal layer, containing a metal material layer with high reflectivity, thus increasing light reflection and improving the light extraction efficiency of the light-emitting diode.

[0034] Optionally, the thickness of the transparent conductive layer is between 100 Å and 1500 Å.

[0035] Reducing the thickness of the transparent conductive layer decreases light absorption, which in turn increases reflected light and improves the light extraction efficiency of the LED. Optionally, the first electrode includes at least an Al layer, which is disposed adjacent to the first semiconductor layer.

[0036] The first electrode contains an Al layer, which can increase the reflection of light radiated from the active layer to the first electrode, especially at the sidewall, and can also increase the light extraction efficiency of the light-emitting diode.

[0037] Optionally, the thickness of the ALD protective layer is between 20 nm and 125 nm.

[0038] The ALD protective layer is relatively thin, ensuring that it does not absorb too much light while maintaining the aforementioned improved metal coverage, thus not affecting the light extraction efficiency of the LED.

[0039] Optionally, the insulating reflective layer includes alternating first and second material layers, wherein the first and second material layers have different refractive indices, and the total number of the first and second material layers is between 35 and 50.

[0040] Increasing the number of stacked insulating reflective layers can increase the wavelength range of its reflection and improve the light extraction efficiency of the light-emitting diode.

[0041] Another embodiment of the present invention provides a light-emitting device, which includes a circuit board and a light-emitting element disposed on the circuit board, the light-emitting element including the light-emitting diode provided in this application. This light-emitting device includes the light-emitting diode of this application, and therefore can achieve good light extraction efficiency and brightness. Example

[0042] This embodiment provides a light-emitting diode, such as Figure 2 As shown, the light-emitting diode 100 at least includes a semiconductor epitaxial stack 120, a first insulating layer 130, an electrode structure, and a second insulating layer 140. The semiconductor epitaxial stack 120 includes a first semiconductor layer 121, an active layer 122, and a second semiconductor layer 123 stacked in sequence. Also referring to Figure 3 , the light-emitting diode 100 further includes a substrate 110. The substrate 110 has opposite front 111 and back 112 surfaces, and the semiconductor epitaxial stack 120 is located on the front 111 side of the substrate 110.

[0043] The material of the substrate 110 can be a substance selected from sapphire (Al2O3), SiC, GaAs, GaN, ZnO, Si, GaP, InP, and Ge, etc., but not limited thereto. The substrate 110 can be a light-transmitting substrate capable of transmitting light in the ultraviolet wavelength band, such as a sapphire substrate.

[0044] The semiconductor epitaxial stack 120 of this embodiment can be any semiconductor epitaxial stack 120 capable of emitting light under voltage. In this embodiment, the semiconductor epitaxial stack 120 can output light in the ultraviolet wavelength range. For example, the light-emitting structure can output light in the near-ultraviolet wavelength band (UV-A), far-ultraviolet wavelength band (UV-B), or deep-ultraviolet wavelength band (UV-C). Exemplarily, the light in the near-ultraviolet wavelength band (UV-A) can have a peak wavelength in the range of 320 nm to 420 nm, the light in the far-ultraviolet wavelength band (UV-B) can have a peak wavelength in the wavelength range of 280 nm to 320 nm, and the light in the deep-ultraviolet wavelength band (UV-C) can have a peak wavelength in the range of 100 nm to 280 nm.

[0045] When the semiconductor epitaxial stack 120 emits light in the ultraviolet wavelength band, each semiconductor layer of the light-emitting structure can include In 0.6 ,

[0046] , 1-x1-y1 , 0.4 , Al y1 Ga 1-x1-y1 N (0≤x1≤1, 0<y1≤1, 0≤x1+y1≤1) material. Among them, the Al component can be represented by the ratio of the total atomic weight including the atomic weights of In, Ga, and Al to the atomic weight of Al. For example, when the Al component accounts for 40%, the Ga component in Al 0.4 Ga 0.6 N can account for 60%.

[0046] The first semiconductor layer 121 in the semiconductor epitaxial stack 120 can be realized by a compound semiconductor such as III-V or II-VI, and can be doped with a first dopant. The first semiconductor layer 121 can be In x1 Al y1 Ga 1-x1-y1The empirical formula of the semiconductor material of N (0 ≤ x1 ≤ 1, < y1 ≤ 1, 0 ≤ x1 + y1 ≤ 1) can be, for example, a material selected from AlGaN, AlN, InAlGaN, etc. The first dopant can be an N-type dopant such as Si, Ge, Sn, Se, Te. When the first dopant is an N-type dopant, the first semiconductor layer 121 doped with the first dopant is an N-type semiconductor layer.

[0047] The active layer 122 is disposed between the first semiconductor layer 121 and the second semiconductor layer 123. The active layer 122 is a layer where electrons (or holes) injected through the first semiconductor layer 121 meet holes (or electrons) injected through the second semiconductor layer 123. As electrons and holes recombine and jump to a lower energy level, light with an ultraviolet wavelength can be generated in the active layer 122. The active layer 122 can have a structure selected from a single-well structure, a multi-well structure, a single quantum well structure, a multi quantum well (MQW) structure, a quantum dot structure, or a quantum wire structure, but is not limited thereto.

[0048] The active layer 122 can include a plurality of well layers and barrier layers. The well layers and barrier layers can have In x2 Al y2 Ga 1-x2-y2 The empirical formula of N (0 ≤ x2 ≤ 1, 0 < y2 ≤ 1, 0 ≤ x2 + y2 ≤ 1). The aluminum component of the well layer can vary according to the emission light wavelength. As the aluminum component increases, the wavelength of the light emitted from the well layer can become smaller.

[0049] The second semiconductor layer 123 is formed on the active layer 122 and can be a compound semiconductor such as a III-V group or a II-VI group, and the second semiconductor layer 123 can be doped with a second dopant. The second semiconductor layer 123 can be a semiconductor material with the empirical formula of In x5 Al y2 Ga 1-x5-y2 N (0 ≤ x5 ≤ 1, 0 < y2 ≤ 1, 0 ≤ x5 + y2 ≤ 1), or can be a material selected from AlInN, AlGaAs, GaP, GaAs, GaAsP, AlGaInP. When the second dopant is a p-type dopant such as Mg, Zn, Ca, Sr, Ba, etc., the second semiconductor layer 123 doped with the second dopant is a p-type semiconductor layer.

[0050] Although not shown, it can be understood that an electron-blocking layer (EBL), etc. can be provided between the active layer 122 and the second semiconductor layer 123. The electron-blocking layer, as a confinement layer of the active layer 122, can reduce the leakage of electrons.

[0051] Refer to Figure 2The semiconductor epitaxial stack 120 includes a first mesa 1201 and a second mesa 1202. The first mesa 1201 is formed by removing a portion of the active layer 122 and the second semiconductor layer 123 by etching the mesa to expose the first semiconductor layer 121. The unetched portion of the semiconductor epitaxial stack 120 forms the second mesa 1202. The second mesa 1202 is the light-emitting area of ​​the light-emitting diode 100. The first mesa 1201 is disposed around the second mesa 1202.

[0052] Similarly, refer to Figure 2 The light-emitting diode 100 also includes a transparent conductive layer 130, which is formed above the second mesa 1202. Specifically, the transparent conductive layer 130 can completely cover the second semiconductor layer 123 exposed on the second mesa 1202, or it can partially cover the second semiconductor layer 123. Figure 2 As shown, in this embodiment, the transparent conductive layer 130 covers a portion of the second semiconductor layer 123. There is a certain distance between the edge of the transparent conductive layer 130 and the edge of the second semiconductor layer 123; that is, the transparent conductive layer 130 is not covered above the second semiconductor layer 123 at the edge of the second mesa 1202. The transparent conductive layer 130 is formed of a transparent conductive material, including but not limited to indium tin oxide (ITO), indium oxide (InO), tin oxide (SnO), cadmium tin oxide (CTO), antimony tin oxide (ATO), aluminum zinc oxide (AZO), zinc tin oxide (ZTO), gallium zinc oxide (GZO), indium tungsten oxide (IWO), zinc oxide (ZnO), gallium phosphide (GaP), indium cerium oxide (ICO), indium tungsten oxide (IWO), indium titanium oxide (ITiO), indium zinc oxide (IZO), indium gallium oxide (IGO), gallium aluminum zinc oxide (GAZO), or combinations of the above materials. In this embodiment, the thickness of the transparent conductive layer 130 is between 100 Å and 1500 Å, and more specifically, for example, between 100 Å and 300 Å, 150 Å and 200 Å, 100 Å and 300 Å, 200 Å and 500 Å, 200 Å and 300 Å, 300 Å and 600 Å, 500 Å and 800 Å, 500 Å and 1000 Å, 1000 Å and 1500 Å. The relatively small thickness of the transparent conductive layer 130 reduces light absorption and increases the amount of light that can be reflected, while simultaneously meeting the operating voltage requirements of the light-emitting diode (LED). Therefore, it can improve the light extraction efficiency of the LED while ensuring its photoelectric effect.

[0053] Refer again Figure 2The light-emitting diode 100 in this embodiment also includes an ALD protective layer 150, an insulating reflective layer 160, and an electrode structure. The ALD protective layer 150 is located above the transparent conductive layer 130, and the insulating reflective layer 160 is located above the ALD protective layer 150. A first electrode via 1501 is formed on the ALD protective layer above the first mesa 1201 and the second mesa 1202, and a second electrode via 1601 is formed in the corresponding region of the first electrode via 1501 on the insulating reflective layer 160. Optionally, the first electrode via 1501 and the second electrode via 1601 are formed with their central axes aligned, and the diameter of the second electrode via 1601 is larger than the diameter of the first electrode via 1501, thereby facilitating the subsequent formation of metal materials. The aforementioned ALD layer 150 is a thin Al2O3 layer formed by atomic layer deposition, with a thickness approximately in the range of 10 nm to 200 nm, and further in the ranges of 20 nm to 150 nm, 20 nm to 125 nm, 50 nm to 100 nm, and 50 nm to 80 nm. This thickness ensures that the ALD protective layer 150 produces almost no light absorption and does not affect the light extraction efficiency of the light-emitting diode.

[0054] The aforementioned electrode structure includes a first electrode formed above the first mesa 1201 and electrically connected to the first semiconductor layer 121, and a second electrode formed on the surface of the second mesa 1202 and electrically connected to the second semiconductor layer 123. The first electrode further includes a first connection electrode 141 located above the first mesa 1201 and connected to the first semiconductor layer 121, and a first metal electrode layer 171 located above the connection electrode 141 and filling the aforementioned second electrode via 1601 and the first electrode via 1501 connected to the first connection electrode 141. The second electrode further includes a second connection electrode 142 located above the transparent conductive layer 130 and connected to the transparent conductive layer 130, and a second metal electrode layer 172 formed above the insulating reflective layer 160 and filling the aforementioned second electrode via 1601 and the first electrode via 1501 connected to the second connection electrode. In an optional embodiment, such as... Figure 3 As shown, the second connecting electrode 142 is formed as a multilayer structure, for example... Figure 3The diagram shows a first layer structure 1421 and a second layer structure 1422. The first layer structure 1421 is adjacent to the transparent conductive layer 130, and the second layer structure 1422 is formed above the first layer structure 1421. The first layer structure 1421 can be a single-layer structure or a multi-layer structure, such as a multi-layer structure comprising two or more metal materials with different refractive indices, such as Cr / Ag, Ti / Ag, Ni / Ag, Ti / Ni / Ag, Ni / Ti / Ag, Cr / Ti / Ag, etc., or a single-layer structure formed of Ag. In a specific example, the first layer structure 1421 is formed of Cr / Ag, forming a reflective metal layer. Ag has a high reflectivity, which can increase the reflection of incident light to improve the light extraction efficiency of the light-emitting diode 100. Cr has good corrosion resistance, which can improve the stability of the second connecting electrode 142. The second layer structure 1422 can be a single-layer or multi-layer structure formed of one or more of copper, tin, silver, tungsten, titanium, etc. The second metal electrode layer 172 can also be formed as a single layer or a multi-layer structure. In this embodiment, the second metal electrode layer 172 is formed as a multi-layer structure, wherein the layer structure adjacent to the second connecting electrode layer 142 is set as an Al layer. Since Al has a high reflectivity, it can further increase the reflection of light incident here.

[0055] Similarly, Figure 3As shown, at the second connecting electrode 142, the ALD protective layer 150 covers the edge of the second connecting electrode 142, that is, the ALD protective layer 150 forms a wrapping state around the edge of the second connecting electrode 142. Since the second connecting electrode 142 contains metal Ag, the above-mentioned arrangement of the ALD protective layer 150 can effectively block the diffusion of metal ions, especially Ag ions, into the semiconductor layer, thereby improving the reliability of the light-emitting diode. In addition, the sidewall of the ALD protective layer 150 (i.e., the sidewall of the first conductive via 1501) and the plane containing the surface of the second semiconductor layer 123 have a first included angle α; the sidewall of the insulating reflective layer 160 (i.e., the sidewall of the second electrode via 1601) and the plane containing the surface of the second semiconductor layer have a second included angle β, and α < β. Further, the first included angle α satisfies: 10° ≤ α ≤ 60°, further, 10° ≤ α ≤ 40°, 10° ≤ α ≤ 30°, 20° ≤ α ≤ 50°, etc. The second included angle β satisfies: 20°≤β≤80°, and further, 20°≤α≤50°, 30°≤α≤60°, 40°≤α≤80°, etc. The aforementioned range and relationship between the first included angle α and the second included angle β ensure a smooth transition between the sidewalls of the first electrode through-hole 1501 and the second electrode through-hole 1601. This improves the adhesion and uniformity of the metal material during the deposition of the second connecting electrode 142 and the second metal electrode layer 172, preventing defects such as cracks and fractures in the metal layer, thereby enhancing the stability and reliability of the electrode structure. (Refer to...) Figure 2 The insulating reflective layer 160 is a DBR structure formed by two insulating material layers with different refractive indices, such as a combination of two materials selected from titanium dioxide (TiO2), silicon dioxide (SiO2), aluminum oxide (Al2O3), and tantalum pentoxide (Ta2O5). In this embodiment, the insulating reflective layer 160 includes alternating layers of titanium dioxide and silicon dioxide, with a total number of stacked layers between 35 and 50, such as 35, 40, 45, 48, or 50 layers. The insulating reflective layer 160 has a large number of stacked layers and a correspondingly larger thickness, which increases its reflection wavelength range and improves the light extraction efficiency of the light-emitting diode.

[0056] like Figure 2 As shown, in this embodiment, a current blocking layer made of insulating material is not provided directly below the second connecting electrode 142 between the transparent conductive layer 140 and the second semiconductor layer 123. Therefore, light absorption can be reduced accordingly, which is beneficial to improving the luminous efficiency of the light-emitting diode.

[0057] To further verify the light extraction efficiency of the LED in this embodiment, the LED in this embodiment is compared with existing technology (…). Figure 1 The light-emitting diodes shown were compared. Figure 4 As shown, the average brightness of the light-emitting diode in this embodiment is significantly improved compared to the prior art, specifically, by nearly 10%. Figure 5 As shown, the average voltage of the light-emitting diode in this embodiment is lower than that of the light-emitting diode in the prior art, specifically, it is reduced by nearly 3%. Therefore, the light-emitting diode in this embodiment has higher photoelectric conversion efficiency and light extraction efficiency.

[0058] Since the second mesa 1202 is the light-emitting mesa of the LED 100, the above description focuses on the relevant settings of the second electrode. It is understood that the first connecting electrode 141 in the first electrode can also be configured as a single-layer or multi-layer metal structure containing an Al layer. In this case, when light radiated by the active layer 122 reaches the first connecting electrode 141, especially its sidewall, it can be effectively reflected, further improving the light extraction efficiency of the LED.

[0059] Similarly, Figure 2 As shown, the light-emitting diode 100 of this embodiment further includes an insulating protective layer 190 and a pad structure. The insulating protective layer 190 covers the surface of the first metal electrode layer 171, the second metal electrode layer 172, and the insulating reflective layer 160. The insulating protective layer 190 can be SiO2, Si3N4, Al2O3, TiO2, ZnO, HfO2, etc. Its thickness is, for example, between 0.5 μm and 5 μm, and more specifically, between 1 μm and 3 μm. The insulating protective layer 190 can help improve the reliability of the light-emitting diode. It is understood that an opening is formed on the insulating protective layer 190 to expose the first metal electrode layer 171 and the second metal electrode layer 171. The pad structure includes a first pad 181 and a second pad 181 formed on the insulating protective layer 190 and spaced apart. The first pad 181 and the second pad 181 are connected to the first metal electrode layer 171 and the second metal electrode layer 172 respectively through the opening on the insulating protective layer 190. Example

[0060] This embodiment provides a light-emitting diode, such as Figure 6 As shown, the light-emitting diode 100 also includes at least a semiconductor epitaxial stack 120, a first insulating layer 130, an electrode structure, an ALD protective layer, and an insulating reflective layer. The aforementioned semiconductor epitaxial stack comprises a first semiconductor layer 121, an active layer 122, and a second semiconductor layer 123 stacked sequentially. The similarities to Embodiment 1 will not be repeated, but the differences are: like Figure 6 As shown, in this embodiment, the second electrode located above the second semiconductor layer 123 includes a second metal electrode layer 172, and no second connection electrode 142 is provided. Figure 7As shown, at this time, the second metal electrode layer 172 fills the second conductive via 1601 and the first conductive via 1501, and is connected to the transparent conductive layer 130. Since the sidewalls of the ALD protective layer 150 and the sidewalls of the insulating reflective layer 160 also have the angular arrangement relationship described in Embodiment 1, the second metal electrode layer 172 has good adhesion and filling uniformity, and also has good reliability and stability.

[0061] In this embodiment, the second metal electrode layer 172 is configured as a multilayer structure, for example... Figure 7 The diagram shows a first metal layer 1721 and a second metal layer 1722, wherein the first metal layer 1721 is disposed adjacent to the transparent conductive layer 130, and the second metal layer 1722 is located above the first metal layer 1721. To increase the reflectivity at the second metal electrode layer 172, the first metal layer 1721 is a material layer with high reflectivity. The first metal layer 1721 can be a single-layer structure or a multi-layer structure, such as a multi-layer structure comprising two or more metal material layers with different refractive indices, for example, a Cr / Ag, Ti / Ag, Ni / Ag, Ti / Ni / Ag, Ni / Ti / Ag, Cr / Ti / Ag, or a single-layer structure formed of Ag. In a specific example, the first metal layer 1721 is, for example, a Ti / Ni / Ag multi-layer structure, where Ag has high reflectivity, which can increase light reflection and improve the light extraction efficiency of the light-emitting diode, and Ti and Ni can increase the adhesion to the transparent conductive layer 130 and the ALD protective layer 150, improving their reliability. The first metal layer 1721 is formed as a reflective electrode layer in the second electrode. In an optional embodiment, the reflective electrode layer (i.e., the first metal layer 1721) at least fills the first electrode via 1501 above the second mesa and covers the edge region of the ALD protective layer 150. Alternatively, as... Figure 7 As shown, the first electrode via 1501 and part of the second electrode via 1601 are filled. The first metal layer 1721 is provided with a certain thickness to ensure sufficient reflectivity. Due to the presence of the ALD layer, the diffusion of metal ions in the first metal layer 1721 into the semiconductor layer can also be prevented to some extent, improving the reliability of the light-emitting diode. The second metal layer 1722 can be a single-layer or multi-layer structure, and it includes at least an Al layer, wherein the Al layer is disposed adjacent to the reflective electrode layer (second metal layer), thereby further increasing the reflection of light.

[0062] Similarly, refer to Figure 7The formation of the ALD protective layer 150 makes the sidewalls of the first electrode through hole 1501 and the second electrode through hole 1601 form a smooth transition. When depositing metal material to form the second metal electrode layer 172, it can improve the adhesion and uniformity of the metal material, prevent defects such as cracks and fractures in the metal layer, and thus improve the stability and reliability of the electrode structure. Example

[0063] This embodiment provides a light-emitting device, such as... Figure 8 As shown, the light-emitting device 200 includes a circuit board 201 and at least one light-emitting unit 202 fixed to the circuit board 201. The light-emitting unit 202 includes a light-emitting diode provided in Embodiment 1 and / or Embodiment 2 of this application. Because the light-emitting device includes a light-emitting diode provided in Embodiment 1 and / or Embodiment 2, it has good light extraction efficiency and better reliability.

[0064] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A light emitting diode, characterized by, At least comprising: a semiconductor epitaxial stack comprising a first semiconductor layer, an active layer and a second semiconductor layer stacked in sequence; the semiconductor epitaxial stack forms a first mesa and a second mesa, a surface of the first mesa is the exposed first semiconductor layer, a surface of the second mesa is the second semiconductor layer, the first mesa is lower than the second mesa, the semiconductor epitaxial stack forms the first mesa and the second mesa on one side as a front surface, and the other side opposite to the front surface as a back surface, the back surface is the light emitting surface of the light emitting diode; an ALD protective layer covering the surfaces and sidewalls of the first mesa and the second mesa, and forming a first electrode via hole above the first mesa and the second mesa; an insulating reflective layer located above the ALD protective layer, forming a second electrode via hole in the corresponding area of the first electrode via hole, at the first electrode via hole, the sidewall of the ALD protective layer and the surface of the second semiconductor layer have a first included angle α, at the second electrode via hole, the sidewall of the insulating reflective layer and the surface of the second semiconductor layer have a second included angle β, and α < β.

2. The light emitting diode of claim 1, wherein, The first included angle α satisfies: 10° ≤ α ≤ 30°.

3. The light emitting diode of claim 1, wherein, The second included angle β satisfies: 30° ≤ β ≤ 60°.

4. The light emitting diode of claim 1, wherein, Further comprising: a transparent conductive layer formed above the second semiconductor layer; an electrode structure, the electrode structure comprises a first electrode formed on the surface of the first mesa and electrically connected with the first semiconductor layer, and a second electrode formed on the surface of the second mesa and electrically connected with the second semiconductor layer; In the direction away from the second semiconductor layer, the second electrode comprises a reflective electrode layer formed above the transparent conductive layer.

5. The light emitting diode of claim 4, wherein, The first electrode via hole exposes the reflective electrode layer, and the ALD protective layer covers the edge area of the reflective electrode layer, the reflective electrode layer comprises two or more metal material layers with different refractive indexes.

6. The light emitting diode of claim 4, wherein, The reflective electrode layer at least fills in the first electrode via hole above the second mesa, and covers the edge area of the ALD protective layer, the reflective electrode layer comprises two or more metal material layers with different refractive indexes.

7. The light emitting diode of claim 5, wherein the first and second semiconductor layers are formed of a nitride semiconductor. The second electrode further comprises a metal electrode layer, the metal electrode layer is located above the insulating reflective layer and fills the first electrode via hole and the second electrode via hole above the second mesa, the metal electrode layer at least comprises an Al layer, and the Al layer is arranged immediately adjacent to the reflective electrode layer.

8. The light emitting diode of claim 6, wherein, The second electrode further comprises a metal electrode layer, the metal electrode layer is located above the insulating reflective layer and fills the second electrode via hole above the second mesa, the metal electrode layer is a Cr / Al metal layer.

9. The light emitting diode of claim 4, wherein, The thickness of the transparent conductive layer is between 100 Å ~ 1500 Å.

10. The light emitting diode of claim 4, wherein, The first electrode at least comprises an Al layer, the Al layer is arranged immediately adjacent to the first semiconductor layer.

11. The light emitting diode of claim 1, wherein, The thickness of the ALD protective layer is between 20 nm ~ 125 nm.

12. The light emitting diode of claim 1, wherein, The insulating reflective layer comprises first material layers and second material layers which are alternately stacked, wherein the first material layers and the second material layers have different refractive indexes, and the total number of the first material layers and the second material layers is between 35 and 50.

13. A light-emitting device, characterized in that, The light emitting element includes a circuit substrate and a light emitting diode disposed on the circuit substrate, the light emitting diode including the light emitting diode according to any one of claims 1 to 12.

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